Already known is a stencil printing device equipped with a stencil master plate ejecting device in which a stencil master plate mounted around the outer circumferential surface of a printing drum is peeled off therefrom by using a peeling claw, and the thus removed stencil master plate is conveyed to a master plate receiving unit by master plate ejecting feed rollers. Such stencil master plate ejecting devices are disclosed for instance in Japanese utility model laid open publication (kokai) No. 58-3266 and Japanese utility model publication (kokoku) No. 04-18867.
Conventionally, such a stencil printing device is provided with stencil master plate detecting means for detecting the presence of a stencil master plate in the path of conveying stencil master plates to an ejected master plate receiving unit, and the state of the stencil master plate detecting means is monitored if it changes from the one indicating the absence of a stencil master plate to the one indicating the presence of a stencil master plate within a prescribed time period after the issuance of the command to start the operation of ejecting a stencil master plate so that a start of a next operation may be permitted when such a sequence of the change of the state of the stencil master plate detecting means took place, and a start of a next operation may be otherwise prohibited as being a case of a failure to properly eject a stencil master plate.
This process of determining the occurrence of a failure to properly eject a stencil master plate is based on the detection of the leading edge of the stencil master plate that is to be ejected as it passes through the conveying path leading to the ejected master plate receiving unit, and, therefore, the succeeding operation of the stencil printing device is permitted as if the ejection of the stencil master plate were completely executed even though it is possible that the leading edge of the stencil master plate to be ejected has passed through the conveying path leading to the ejected master plate receiving unit but may have failed to be delivered to the ejected master plate receiving unit due to some fault of the system.
If the succeeding operation of the stencil printing device is carried out without the removed stencil master plate being properly conveyed to the ejected master plate receiving unit, the rotation of the printing drum may be obstructed by the stencil master plate accidentally remaining in the master plate ejecting unit, and the stencil master plate newly mounted on the printing drum may be smeared by the ink adhering to the preceding stencil master plate which failed to be properly ejected. Furthermore, the previous stencil master plate accidentally remaining in the master plate ejecting unit will prevent the proper ejection of the succeeding stencil master plates, and the fault in the master plate ejecting unit will be progressively worsened, eventually requiring a major servicing work to restore the stencil printing device into its properly operable condition.